Polychloro-alpha-hydroxybenzylphosphonic and phosphinic derivatives as plant growth control agents



United States Patent 3,515,537 POLYCHLOR0-a-HYDROXYBENZYLPHOSPHONIC ANDPHOSPHINIC DERIVATIVES AS PLANT GROWTH CONTROL AGENTS Edward D. Weil,Yonkers, Edwin Dorfman, Grand Island, and Jerome Linder, Niagara Falls,N.Y., assignors to Hooker Chemical Corporation, Niagara Falls, N.Y., acorporation of New York No Drawing. Original application Mar. 14, 1966,Ser. No. 533,792. Divided and this application Nov. 29, 1967, Ser. No.701,798

Int. Cl. A01n 9/36, 13/00 US. CI. 71-86 6 Claims This is a division ofthe parent application Ser. No. 533,792, filed Mar. 14, 1966.

This invention is concerned with new and useful com positions of matterknown as polychlorinated-alpha-hydroxybenzylphosphonic and phosphinicacids and esters thereof.

The compounds of the invention are described by the general formulawhere at least one and a maximum of two of the substituents X, Y and Zis where w is an integer from two to five, and the remainingsubstituents are selected from the group consisting of hydrogen, alkoxy,aryloxy, and no more than one hydroxy. The new compounds of theinvention are high boiling liquids or solids.

It is preferred that there be three chlorine substituents on the benzenering. Thus, the u-hydroxytrichlorobenzyl substituents may have thechlorine atoms in the 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or 3,4,5-configuration. However the di-, tetra-, pentachlorobenzyl compounds arealso to be included within the scope of this invention including the2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5- 2,3,4,5-, 2,3,4,6-, 2,3,5,6-, and2,3,4,5,6- configurations.

The compounds of the invention bearing a singleu-hydroxypolychlorobenzyl group are designated asa-hydroxypolychlorobenzylphosphonic acids and derivatives thereof, andthe compounds of the invention bearing two u-hydroxypolychlorobenzylgroups are designated as his oz hydroxypolychlorobenzyl) phosphinicacids and derivatives.

The lower alkoxy substituents which may be present in the compounds ofthe invention have from one to twelve carbon atoms. Representativesamong these may be methoxy, ethoxy, propoxy, isopropoxy, butoxy,sec-butoxy, isobutoxy, amyloxy, hexyloxy, cyclohexyloxy, octyloxy,decycloxy, lauryloxy, and the like. Also included are lower alkoxygroups substituted by halogen, as for example 2- chloroethoxy, alsolower alkoxy groups substituted by a hydroxy, such as 2-hydroxyethoxy,also lower alkoxy groups substituted by a lower alkoxy, such as2-ethoxyethoxy, also lower alkoxy groups substituted by an aryl group,such as benezyloxy. As examples of aryloxy groups which may be presentas substituents may be named phenoxy, cresoxy, chlorophenoxy, naphthoxy,and the like. Alkyl and alkoxy groups used herein have 1-12 carbonatoms.

The compounds of the invention bearing a hydroxy and/ or a hydrogengroup on the phosphorus atom are acids and as such readily form salts,such as the sodium, potassium, calcium, zinc, copper, ammonium,alkylammonium,

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dimethylammonium, trimethylammonium, and other lower alkylammoniumsalts, such salts being included within the scope of the invention, withthe water-soluble salts being preferred.

The compounds of the invention are preferably synthesized by thereaction of phosphorous acid, hypophosphorous acid, or an ester thereofwith the polychlorobenzaldehyde.

An advantage of the novel method of this invention is that it lendsitself to the use of various grades of purity, by itself or incombination with other biologically active compositions. For example,these herbicidal compositions offer the advantage of compatibility witha host of other herbicides including the triand tetrachlorophenylaceticacids and the sodium borates and calcium borates, 2,4-D and otherherbicidal phenoxy aliphatic acids and esters, simazine and otherherbicidal triazines, monuron, fenuron, diuron and other herbicidalureas, herbicidal chlorates, herbicidal petroleum oils,hexachlorocyclopentadiene, pentachlorophenol, dinitro-o-alkylphenols,sodium trichloroacetate and sodium 2,2-dichloropropionate, and withvarious adjuvants and diluents well known to the art. Thus, theseherbicides may be used by themselves or made the subject of liquid orsolid formulations ranging from the very simple to the most elegant. Forexample, if it is desired these compositions may be made the subject ofa liquid formualtion by diluting, dispersing, dissolving or emulsifyingwith a surface active adjuvant or combination of these adjuvants inorganic solvents such as petroleum hydrocarbons, alcohols, ketones,esters, glycols or combination thereof. 0r alternatively, the novelherbicides may be made up as solid formulations of powders, dusts,wettable dusts, granules and pellets using solid diluents such as talcs,clays, flours, starches, diatomaceous earths, mica, alkaline earthlimes, carbonates and phosphates either finely divided, granular orpelleted in form.

These solid and liquid formulations facilitate handling and applicationand sometimes enhance herbicidal activity to more than an additivedegree.

The liquid compositions, whether solutions or dispersions of the activeagents in a liquid solvent and also the wettable powder or dustcompositions of this invention may contain as a conditioning agent oneor more surface active agents in amounts sufficient to render thecomposition readily dispersible in water. By the term surface activeagents are included wetting agents, dispersing agents, emulsifyingagents and the like. A satisfactory but not complete list of such agentsis set forth in an article in Soap and Chemical Specialties, vol. 31,No. 7, pages 5061; No. 8, pages 48-61; No. 9, pages 52-67, and No. 10,pages 38 (67) 1955. Other sources of adjuvant materials is set forth inBulletin E-607 of the Bureau of Entomology and Plant Quarntine of theUnited States Department of Agriculture.

While the manner and method of application of the inventive compositionsis varied and largely dependent upon the climatic conditions, croptreated, the weeds to be eradicated, the equipment available and theconvenience of the user, a preferred embodiment of this invention is toapply our new herbicide as a spray after making it up as a liquidformulation comprised of several times its weight of a petroleumhydrocarbon solvent such as petroleum naphtha, kerosene, diesel oil,xylene, Weed oil, fuel oil, etc., optionally with small quantities of anemulsifier such as a commercial polyoxyethylene ether and a surfactantsuch as alkylaryl sulfonate mixture. This type of mixture is eithersprayed without further dilution or emulsified with water and sprayed onthe weed population or on the soil where weed growth is to be prevented.

The rate of application of the inventive herbicidal composition cannotbe precisely stated due to varying degrees of resistance possessed bythe weed species and crop, the stage of weed and crop growth, the soiltype and climatic conditions, but in general, the rates will be at leastone-quarter of a pound of herbicide per acre and for reasons of costwill seldom exceed four hundred pounds per acre with the preferredfalling within five-tenths to fifty pounds per acre. Where the weeds orbrush are in an early stage of growth, they being more susceptible, willfrequently respond to the rates from one-half to eight pounds per acrewhile older weeds or brush that are to be totally eradicated may requirerates in excess of ten pounds per acre. In those instances where wellestablished brush is encountered or where the weed population has beenallowed to accumulate unchecked or Where mature plants are encountered,applications of up to fifty and even beyond this rate may be required.For eradication of deeply-rooted herbicide resistant perennial weedssuch as field bind-weed or for long term sterillization rates of tenpounds up to several hundred pounds per acre may be necessary.

The compound of the invention may also be employed at sublethal rates toproduce stunting of plants. For example, the growth of brush under powerlines may be retarded in this way.

The compositions are most effective when applied as a pre-emergentherbicide, although the compositions can be applied post-emergent, aswell.

To illustrate the preparation of these compounds, the following examplesare given.

EXAMPLE 1 Dimethyl-a-hydroxy-2,3,6-trichlorobenzylphosphonate A mixtureof 21 parts of 2,3,G-trichlorobenzaldehyde and parts of dimethylphosphite was heated under refiux by steam at 100 C. for 24 hours. Themixture was then washed with hexane and dissolved in benzene. On coolingand partial evaporation, a colorless solid crystallized out and wasremoved by filtration, to obtain parts of product, 139.5140.5 C. Theinfrared spectrum revealed a hydroxyl but no carboxyl group.

Analysis.Calculated for C H Cl O (percent): CI, 33.3. Found (percent):Cl, 32.7.

EXAMPLE 2 Bis(a-hydroxy-2,3,6-trichlorobenzyl)phosphinic acid A mixtureof 42 parts of 2,3,6-trichlorobenzaldehyde and 93 parts ofhypophosphorous acid (calculated on 100% basis) was heated for 6 hoursat 90-105 C. under nitrogen. The cooled product was triurated withwater, filtered, dissolved in 3 percent aqueous caustic, filtered andreprecipitated with excess hydrochloric acid. The P oduct was filtered,Washed with water and dried to obtain 36 parts of colorless crystallinesolid, M.P. 179-183 C. Titration with 0.1 N NaOH to form the solublesodium salt showed a neutraliziation equivalent of 490 (theory 483).

Analysis.Calculated for C H CI PO (percent): Cl, 44.1. Found (percent):Cl, 43.2.

EXAMPLE 3 Diethyl-a-hydroxy-2,3,6-trichlorobenzylphosphonate A mixtureof 21 parts of 2,3,6-trichlorobenzaldehyde and 18 parts of diethylphosphite was heated at 100 C. for 20 hours. The mixture was thencrystallized from a benzene-hexane mixture to obtain 20 parts of acolorless gummy solid having the proper analysis for the de' siredadduct.

Analysis.-Calculated for C H O PCI (percent): Cl, 31.5. Found (percent):CI, 30.2.

4 EXAMPLE 4 Diethyl-m-hydroxy-2,3,6- and 2,4,5-trichlorobenzylphosphonate A mixture of 21 parts of a technical trichlorobenzaldehyde,analyzing -90% 2,3,6- and l020% 2,4,5- trichlorobenzaldehyde, byinfrared, was reacted with diethyl phosphite as in Example 3 to obtain amixed diethyl-a-hydroxytrichlorobenzylphosphonate, a gummy colorlesssemi-solid.

Analysis.Calculated for C H O PCl Cl, 31.5. Found (percent): Cl, 30.5.

EXAMPLE 5 Diphenyl-u-hydroxy-2,3,6-trichlorobenzylphosphonate A mixtureof 21 parts of 2,3,6-trichlorobenzaldehyde and 25 parts of diphenylphosphite was heated at C. for 24 hours. The resultant mixture, glassyupon cooling, was leached with hot hexane to remove any unreactedstarting materials. The remaining material was a light gray solid, M.P.53-56 C. The infrared spectrum showed a hydroxyl but no carboxyl group.

Analysis.Calculated C H O Cl P (percent): 24.1. Found (percent): CI,25.9.

The new compounds of the invention have utility as chemicalintermediates, as pesticides, and as fire retardant ingredients ofresins and polymers.

Other polymers in which the composition of this invention may beincorporated include the polyesters, alkyds and paint vehicles, such asbodied linseed oil, nylon, diallyl phthalates and phthalates,isocyanates and polycarbonates. Polycarbonates are thermoplastic resinsformed from a dihydroxy compound and a carbonate diester. The moreimportant commercial polycarbonates are made from para,paraisopropylidenediphenol and phosgene. Polyesters are thermoplasticresins produced by the reaction of dibasic acids and dihydroxycompounds. The unsaturated polyesters can be further polymerized bycrosslinking. Alkyds are in many respects similar to polyesters, butalkyds utilize unsaturated fatty acids. Resins within the scope of thisinvention include the condensation reaction products of phenol andaldehyde, e.g., novolacs and thermoplastic polymers ofbis-(4-hydroxyphenyl)-2,2-propane and epichlorohydrin (trade name ofphenoxy). The polymeric compositions and coatings of this inventioninclude high molecular weight polymers and resins as well as theintermediate molecular weight materials utilized for coatings andpaints. The polymers embraced within the scope of this invention includethe homopolymers and copolymers of unsaturated aliphatic, alicyclic, andaromatic hydrocarbons. The most common of these are formed fromethylene, propylene, butadiene and styrene.

They have been found to have surprising activity as herbicides, as shownby the following example:

EXAMPLE 6 An area seeded with corn, and having a natural infestation ofbroad-leaf weeds, predominantly ragweed, lambsquarters and pigweed, wassprayed pre-emergence with the products of 'Examples 1-5 at the rate of8 pounds per acre. In the case of the products of Examples 1, 3, 4 and5, the active ingredient was first dissolved in 3-5 parts of xylene andemulsified with water using Atlox 3335P, a commercial non-ionicemulsifier. The product of Example 2 was dissolved in water as thesodium salt. In each case, except with the product of Example 2, thecorn germinated and grew normally, while the broad-leaf weeds weretotally controlled. The product of Example 2 gave complete weed controlat 8 pounds per acre but also corn damage; however, at 2 pounds peracre, the corn was undamaged and the Weeds were well controlled.

The use of the compounds as fire-retardant additives for resins isillustrated by the following example.

(percent) EXAMPLE 7 A polyester composed of 8.9 moles oftrimethylolpropane, 5 moles of adipic acid and 1 mole of phthalic acidwas cooked between 160 and 220 degrees Centigrade until the acid numberdeclined below 1. Then 5 parts of the product of Example 1, 20 parts ofthis polyester, 1.5 parts of water, 0.25 part of 'Emulphor EL719 (apolyoxyethyL ated vegetable oil which is a commercial emulsifying agent)and 0.1 part of N-methylmorpholine were mixed at room temperature. Tothis mixture were added 35 parts of the prepolymer formed by thereaction of 20 parts of the above polyester with 80 parts of toluenedilsocyanate. The mixture was stirred thoroughly, poured into a mold,and allowed to expand and cure at room temperature to give a foam of 4pounds/cu. ft. density. This foam in a standard test was classified asslow burning. A comparison foam made as above but omitting the productof Example 1 was classified as rapid burning.

Since many changes could be made in the above compounds and methods byone of ordinary skill in the art without departing from the scope of theinvention, it is intended that all matter contained in the abovedescription shall be illustrative and not in a limiting sense.

We claim:

1. A method for the control of plant growth in a locus which comprisesapplying to the locus a growth regulating amount of the compound havingthe formula where at least one and a maximum of two of the substituentsX, Y and Z is where w is an integer between two and five and theremaining substituents are selected from the group consisting ofhydrogen, alkoxy having from 1 to 12 carbon atoms, hydrocarbyl aryloxyhaving from 6 to 12 carbon atoms and no more than one hydroxy group, andthe inorganic and unsubstituted lower alkyl ammonium salts of thosecompounds having hydrogen and/or hydroxy substituents on the phosphorusatom.

2. The process of claim 1 wherein the compound is diphenyltrichloro-a-hydroxybenzylphosphonate.

3. The process of claim 1 wherein the compound is bis(a-hydroxy-trichlorobenzyl) phosphinic acid.

4. The process of claim 1 wherein the compound is diethyltrichloro-a-hydroxybenzylphosphonate.

5. The process of claim 1 wherein the compound is diethyl2,3,6-trichloro-u-hydroxybenzylphosphonate.

6. The process of claim 1 wherein the compound is dimethyltrichloro-a-hydroxybenzylphosphonate.

References Cited UNITED STATES PATENTS 3,223,514 12/1965 Gradsten 71-862,174,019 9/1959 Sullivan 260-6065 2,929,759 3/ 1960 Gilbert et a1.260-953 3,342,908 9/1967 Birurm 260-953 3,350,192 10/1967 Richter 71-863,351,681 11/1967 Deinet 71-86 LEWIS GOTTS, Primary Examiner G. HOLLRAH,Assistant Examiner US. Cl. X.R.

1. A METHOD FOR THE CONTROL OF PLANT GROWTH IN A LOCUS WHICH COMPRISESAPPLYING TO THE LOCUS A GROWTH REGULATING AMOUNT OF THE COMPOUND HAVINGTHE FORMULA